The present invention generally relates to interferometers for determining the spatial direction of incoming radio waves referenced to an array of spaced antenna elements, and more particularly to an interferometer wherein all spatial frequencies generated by a signal and intercepted by the array are derived from a signal processing technique which utilizes real time convolution of functions in the spectral frequency domain. The signal processing technique is applied to an array of widely spaced pairs of antenna elements in order to form a single beam which is readily scannable. The system circumvents the shortcomings normally encountered in using interferometers, such as ambiguities which arise due to grating lobes and extreme vulnerability to interference due to the difficulty or inability for the interferometer to readily distinguish between two signals within the array system's field of view and within the receiver passband. The signal processing technique according to the invention differs from systems that sample spatial location, as practiced by collimating reflector systems and phased arrays, and from those systems which sample all spatial locations simultaneously, as practiced in adaptive array systems.